Gliederung

Objective: To determine the uselfulness of the combined use of motor and language tract DTI FT and intraoperative subcortical mapping for surgical removal of gliomas.

Methods: 110 patients with gliomas (90 low and 20 high grade) were submitted to surgery with the aid of motor and language mapping (ISM). DTI-FT data for CST, IFO, SLF, UNC were available at the time surgery. DTI-FT was acquired by a 3-T MR scanner with a single-shot EPI sequence (TR/TE 8986/80 msec, b=1000 s/mm) with gradients applied along 32 non collinear directions. Data were transferred to the neuronavigational system. Functional subcortical sites identified during subcortical mapping were correlated with fiber tracts depicted by DTI-FT. The impact of the combined use of DTI FT and subcortical mapping on duration and modalities of surgical procedures, and on functional outcome of the patients was also evaluated.

Results: In high grade gliomas DTI-FT depicted tracts mostly at the border of the tumor, in low grade gliomas the fibers were frequently located inside the tumor mass. There was a high correlation between DTI-FT and ISM (sensitivity for CST=95%, language tracts=97%). For a proper reconstruction of the tracts, it was necessary to use a low FA threshold for the fiber tracking algorythm and to position additional regions of interest (ROIs). The combination of DTI-FT and ISM decreased the duration of surgery, patient fatigue and intraoperative seizures.

Conclusions: Our data indicate a good agreement between DTI-FT data and those obtained during subcortical mapping. When used in combination with subcortical mapping, DTI-FT offers the opportunity to quickly find the fibers associated with motor or language functions during surgery. The clinical relevance of this combined approach comes from the fact that it further enhances surgical safety maintaining a high rate of functional preservation.